Have you learned about hashes yet? You are in need of an algorithm, and the one that you need will most likely involve the use of a hash. Something like this: 
declare a hash (e.g. "my %lines."
open the first input file
while reading the first input one line at a time
   use the line as a hash key and assign "1" as the hash value
close the file

open output.file1 to hold "matching lines"
open output.file2 to hold "distinct lines"

open the second input file
while reading the second input one line at a time
   if the current line exists as a hash key and the hash value is "1"
     print this line to the "matching lines" file
     increment the hash value
   otherwise
     print this line to the "distinct lines" file (maybe include the f
+ile name)

having read all input, now loop over all the keys of the hash
   if the hash value assigned to this key is still "1"
     print this hash key to the "distinct lines" file (maybe include t
+he file name)

[download]
I think you'll find that the actual perl code for that will be somewhat shorter than what I've written, but (since I assume this is homework) you should write the code. There are lots of places to read about hashes in Perl. Have you checked the Tutorials here at the Monastery?

In reply to Re: comparing contents of the file by graff
in thread comparing contents of the file by Ms.Ranjan

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